From 06ffa16694b315380c9b2ebafe06d83873f2a78d Mon Sep 17 00:00:00 2001 From: Sandrine Bailleux Date: Thu, 20 Aug 2020 11:17:41 +0200 Subject: [PATCH] doc: Recommend using C rather than assembly language Add a section for that in the coding guidelines. Change-Id: Ie6819c4df5889a861460eb96acf2bc9c0cfb494e Signed-off-by: Sandrine Bailleux --- docs/process/coding-guidelines.rst | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/docs/process/coding-guidelines.rst b/docs/process/coding-guidelines.rst index 97086047d..a8a84549a 100644 --- a/docs/process/coding-guidelines.rst +++ b/docs/process/coding-guidelines.rst @@ -441,6 +441,25 @@ unsigned integer on all systems, cast it to ``unsigned int``. These guidelines should be updated if additional types are needed. +Favor C language over assembly language +--------------------------------------- + +Generally, prefer code written in C over assembly. Assembly code is less +portable, harder to understand, maintain and audit security wise. Also, static +analysis tools generally don't analyze assembly code. + +There are, however, legitimate uses of assembly language. These include: + + - Early boot code executed before the C runtime environment is setup. + + - Exception handling code. + + - Low-level code where the exact sequence of instructions executed on the CPU + matters, such as CPU reset sequences. + + - Low-level code where specific system-level instructions must be used, such + as cache maintenance operations. + -------------- *Copyright (c) 2020, Arm Limited and Contributors. All rights reserved.*